US6937832B2 - Process cartridge, mountable to an image forming apparatus, having first contact portion to be guided by a guide when mounted and second contact portion to limit cartridge rotation or movement when mounted, and image forming apparatus mounting such a process cartridge - Google Patents

Abstract

A process cartridge is detachably mountable to a main assembly of an electrophotographic. The cartridge includes a photosensitive drum; a process device; and a first contact portion provided on a bottom surface of a cartridge frame provided at one longitudinal. The first contact portion is guided by a first assembly side guide when the cartridge is mounted. The cartridge also includes a cartridge coupling disposed above the first portion, the coupling being engageable with an assembly side coupling to receive a rotational force from the assembly; and a second contact portion disposed behind the first portion with respect to the mounting direction. The second portion limits rotation of the cartridge. The cartridge also includes; a positioning portion projected outwardly and provided at the other longitudinal end of the drum, the positioning portion being guided by a second assembly side guide, and being positioned to a second assembly side receiving portion.

Description

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to a process cartridge removably mountable in an electrophotographic image forming apparatus, and an electrophotographic image forming apparatus.

Here, an electrophotographic image forming apparatus is an apparatus which forms an image on a recording medium with the use of an electrophotographic-image-forming method. Examples of an electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (for example, a laser printer, an LED printer, etc.), a facsimile machine, a wordprocessor, a combination of two or more of the preceding apparatuses (a multifunction printer, etc.), etc.

A process cartridge is: a cartridge in which a charging means, a developing means or a cleaning means, and an electrophotographic photoconductive member, are integrally disposed, and which is removably mountable in the main assembly of an image forming apparatus; a cartridge in which a minimum of one among a charging means, a developing means, and cleaning means, and an electrophotographic photoconductive member, are integrally disposed, and which is removably mountable in the main assembly of an image forming apparatus; or a cartridge in which a minimum of a developing apparatus and an electrophotographic photoconductive member are integrally disposed, and which is removably mountable in the main assembly of an image forming apparatus.

A process-cartridge system, which has an electrophotographic photoconductive member, and a single or a plurality of processing means which act on the electrophotographic photoconductive member, integrally disposed in a cartridge removably mountable in the main assembly of an image forming apparatus, has long been employed by an electrophotographic image forming apparatus which uses an electrophotographic-image-forming process. According to a process-cartridge system, an apparatus can be maintained by a user him/herself; it is unnecessary to hire a service person. Thus, the employment of a cartridge system drastically improves the operational efficiency of the apparatus. Therefore, a cartridge system has been widely used in the field of an image forming apparatus.

In order to obtain an image of good quality with the use of an electrophotographic image forming apparatus employing a process-cartridge system, it is essential that the process cartridge is properly mounted in a predetermined position within the main assembly of the electrophotographic image forming apparatus, and also that the various electrical contacts, driving-force transmitting portions, etc., on the cartridge side are correctly connected to their counterparts on the main-assembly side of the image forming apparatus; it is essential that the two sides are correctly interfaced.

FIG. 31 shows a process cartridge CR, andFIG. 32 shows a process-cartridge mounting guide GL of the main assembly PR of an image forming apparatus.FIG. 33 shows an image forming apparatus employing the process cartridge CR.

Referring toFIGS. 31-33, in order to guide the process cartridge CR and accurately position the process cartridge CR in the image-forming-apparatus main assembly PR when mounting the process cartridge CR into the image-forming-apparatus main assembly PR or removing it therefrom, the process cartridge CR is provided with a positioning boss CB, the axial line of which coincides with the axial line of the photoconductive drum, as an electrophotographic photoconductive member, in the process cartridge CR, whereas the image-forming-apparatus main assembly is provided with a process-cartridge mounting guide GL, which guides the process cartridge CR by the positioning boss CB thereof. As a user inserts the process cartridge CR to a predetermined point in the image-forming-apparatus main assembly PR, along the process-cartridge mounting guide GL, the process cartridge CR comes into contact with the stopper portion P of the image-forming-apparatus main assembly PR, being thereby prevented from further rotating about the axial line of the positioning boss CB. Apparatuses having the above-described structure have been put to practical use.

The present invention is a result of further technical developments of the above-described prior art.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a combination of a process cartridge and an electrophotographic image forming apparatus employing a process-cartridge system, in which the cartridge is more reliably mounted into, or dismounted from, the main assembly of the image forming apparatus.

Another object of the present invention is to provide a combination of a process cartridge and an electrophotographic image forming apparatus employing a process-cartridge system, in which the process cartridge is more accurately positioned relative to the main assembly of the image forming apparatus when the process cartridge is mounted into the main assembly.

Another object of the present invention is to provide a combination of a process cartridge and an electrophotographic image forming apparatus employing a process-cartridge system, in which the process cartridge remains more stable when the process cartridge is mounted into the main assembly.

Another object of the present invention is to provide:

a process cartridge removably mountable in the main assembly of an electrophotographic image forming apparatus, comprising:

an electrophotographic photoconductive drum;

a single or a plurality of processing means which act on the photoconductive drum;

a first contact portion which: is a part of one of the end portions, in terms of the lengthwise direction of the photoconductive drum, of the bottom surface of a cartridge-supporting frame for supporting the photoconductive drum; is guided by a first cartridge-guiding portion of the apparatus main assembly of the image forming apparatus, when the process cartridge is mounted into the proper cartridge position in the apparatus main assembly; is located on the front side in terms of the direction in which the process cartridge is inserted into the proper cartridge position in the main assembly; and is caught and supported by a first catching and supporting portion of the apparatus main assembly, when the process cartridge is mounted into the proper cartridge position in the apparatus main assembly;

a coupler, which: is located above the first contact portion; coupler with the coupler of the apparatus main assembly to receive a rotational driving force; and accurately positions the photoconductive drum;

a second contact portion, which: is a part of one of the end portions, in terms of the lengthwise direction of the photoconductive drum, of the bottom surface of the cartridge-supporting frame for supporting the photoconductive drum; is located on the rear side with respect to the first contact portion, in terms of the cartridge-mounting direction; and prevents the process cartridge from rotating in the rotational direction of the photoconductive drum more than a predetermined angle, when the process cartridge receives the rotational driving force from the apparatus main assembly after the proper mounting of the process cartridge into the apparatus main assembly; and

a positioning portion, which: is on the outward side of one of the lengthwise ends, in terms of the lengthwise direction of the photoconductive drum, of the cartridge-supporting frame for supporting the photoconductive drum; is guided by a second cartridge-guiding portion of the apparatus main assembly, when the process cartridge is mounted into the proper position in the apparatus main assembly; and is accurately positioned by a second catching and supporting portion of the apparatus main assembly, when the process cartridge is mounted into the proper cartridge position in the apparatus main assembly, and,

an electrophotographic image forming apparatus in which the above described process cartridge is removably mountable.

Another object of the prevent invention is to provide:

a process cartridge removably mountable in the main assembly of an electrophotographic image forming apparatus, comprising:

an electrophotographic photoconductive drum;

a single or a plurality of processing means which act on the photoconductive drum;

a first contact portion, which: is a part of one of the end portions, in terms of the lengthwise direction of the photoconductive drum, of the bottom surface of a cartridge-supporting frame for supporting the photoconductive drum; is guided by a first cartridge-guiding portion of the apparatus main assembly of an image forming apparatus, when the process cartridge is mounted into the proper cartridge position in the apparatus main assembly; is on the front side in terms of the direction in which the process cartridge is inserted into the proper cartridge position in the main assembly; and is caught and supported by a first catching and supporting portion of the apparatus main assembly, when the process cartridge is mounted into the proper cartridge position in the apparatus main assembly; and

a second contact portion which is on the rear side with respect to the first contact portion in terms of the cartridge-mounting direction; is a part of the cartridge-supporting frame; and comes into contact with the counterpart of the apparatus main assembly to prevent the process cartridge from being moved by the pressure generated by transferring means of the apparatus main assembly, as the transferring means and photoconductive drum are pressed against each other, after the proper mounting of the process cartridge into the apparatus main assembly, and,

an electrophotographic image forming apparatus in which the above described process cartridge is removably mountable.

These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of the image forming apparatus in one of the preferred embodiments of the present invention, in which a process cartridge in accordance with the present invention has been properly mounted, describing the general structure thereof.

FIG. 2 is a schematic sectional view of the process cartridge in the preferred embodiment of the present invention, illustrating the structure thereof.

FIG. 3 is a perspective view of the process cartridge in accordance with the present invention shown in FIG.2.

FIG. 4 is another perspective view of the process cartridge in accordance with the present invention shown in FIG.2.

FIG. 5 is an exploded perspective view of the drum-frame unit of the process cartridge in accordance with the present invention.

FIG. 6 is a perspective view of the drum-frame unit of the process cartridge in accordance with the present invention.

FIG. 7 is a perspective view of the side holder of the drum-frame unit.

FIG. 8 is a plan view of the charge-roller driving means, describing the structure thereof

FIG. 9 is an exploded perspective view of the charge-roller driving means, illustrating the structure thereof.

FIG. 10 is a perspective view of the process-cartridge driving mechanism, in the preferred embodiment of the present invention.

FIG. 11 is a schematic sectional view of the gear train of the process-cartridge driving mechanism shown inFIG. 10, illustrating the structure thereof.

FIG. 12 is a plan view of the gear train of the process-cartridge driving mechanism shown inFIG. 10, describing the structure thereof.

FIG. 13 is a perspective view of the process-cartridge driving mechanism, in another embodiment of the present invention, illustrating the structure thereof.

FIG. 14 is a schematic sectional view of the process-cartridge driving mechanism shown inFIG. 13, illustrating the structure thereof.

FIG. 15 is a plan view of the process-cartridge driving mechanism shown inFIG. 13, illustrating the structure thereof.

FIG.16(a) is a perspective view of the toner-sealing member in the preferred embodiment of the present invention, and FIG.16(b) is a sectional view of the same toner-sealing member.

FIG. 17 is a perspective view of the toner-storage developing-means frame, and the frame lid, of the cartridge in the preferred embodiment of the present invention, illustrating how they are joined.

FIG. 18 is a drawing for describing how the toner-sealing member is joined with the toner-storage developing-means frame.

FIG. 19 is an exploded perspective view of the development unit of the process cartridge in accordance with the present invention.

FIG. 20 is a perspective view of the development unit in FIG.19.

FIG. 21 is a drawing for illustrating how the cleaning members of the process cartridge in accordance with the present invention are attached.

FIG. 22 is a schematic sectional view of an image forming apparatus, illustrating how the process cartridge is mounted into the image forming apparatus.

FIG. 23 is a schematic sectional view of the image forming apparatus, illustrating how the process cartridge is mounted into the image forming apparatus.

FIG. 24 is a perspective view of one of the cartridge-guiding portions of the image forming apparatus in the preferred embodiment of the present invention.

FIG. 25 is a perspective view of the other cartridge-guiding portion of the image forming apparatus, in the preferred embodiment of the present invention.

FIG. 26 is a drawing for illustrating how the process cartridge is accurately positioned relative to the image forming apparatus.

FIG. 27 is a drawing for illustrating how the process cartridge is accurately positioned relative to the image forming apparatus.

FIG. 28 is a drawing for illustrating how the process cartridge is accurately positioned relative to the image forming apparatus.

FIG. 29 is a schematic drawing of one of the modifications of the contact portions of the process cartridge in accordance with the present invention.

FIG. 30 is a schematic drawing of another modification of the contact portion of the process cartridge in accordance with the present invention.

FIG. 31 is a perspective view of a process cartridge in accordance with the prior arts.

FIG. 32 is a perspective view of one of the cartridge-guiding portions of an image forming apparatus in accordance with the prior arts.

FIG. 33 is a schematic sectional view of an image forming apparatus in accordance with the prior arts, which is properly holding the process cartridge in accordance with the prior arts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a combination of a process cartridge and an electrophotographic image forming apparatus, in accordance with the present invention, will be described in more detail with reference to the appended drawings.

In the following description of the present invention, the lengthwise direction of a process cartridge is the direction intersecting (roughly perpendicular) the direction in which a process cartridge is mounted into, or removed from, the main assembly of an image forming apparatus. It is parallel to the surface of a recording medium, and intersects (roughly perpendicular) the direction in which the recording medium is conveyed. The right or left direction is the right or left direction of the recording medium as the recording medium is seen from the rear side in terms of the recording-medium conveyance direction. The top surface of a process cartridge is the surface of the process cartridge which will be on the top side after the proper mounting of the process cartridge in the main assembly of an image forming apparatus, and the bottom surface of the process cartridge is the surface of the process cartridge which will be on the bottom side after the proper mounting of the process cartridge in the apparatus main assembly.

FIG. 1 shows one of the preferred embodiments of an electrophotographic image forming apparatus in accordance with the present invention. In this embodiment, a process cartridge B, shown inFIG. 2, is removably mountable in this electrophotographic image forming apparatus.FIG. 1 is a schematic drawing for illustrating the structure of this electrophotographic image forming apparatus, which is properly holding the process cartridge B shown in FIG.2.FIG. 2 is a schematic drawing for illustrating the structure of the process cartridge B.

As for the order of description, the general structure of the process cartridge B and the general structure of the electrophotographic image forming apparatus employing the process cartridge B will be first described. Then, the structure of the mechanism of the image-forming-apparatus main assembly for guiding the process cartridge B when the process cartridge B is mounted into, or removed from, the main assembly of the electrophotographic image forming apparatus will be described.

(General Structure)

Referring toFIG. 1, the electrophotographic image forming apparatus A (which hereinafter will be referred to simply as the “image forming apparatus”) in this embodiment is a laser-beam printer, and has an electrophotographicphotoconductive member7 in the form of a drum (which hereinafter will be referred to simply as the “photoconductive drum”), as an image bearing member, which comprises an aluminum cylinder, and a photoconductive layer, that is, a layer of organic photoconductive substance, coated on the entirety of the peripheral surface of the aluminum cylinder.

A beam of light carrying image-formation information is projected onto thephotoconductive drum7 from anoptical system1, forming a latent image on thephotoconductive drum7. This latent image is developed into a toner image with the use of developer (which hereinafter may be referred to as “toner”).

In synchronism with the formation of the toner image, a single or a plurality of sheets of arecording medium2 in thesheet feeder cassette3aare fed one by one into the apparatus main assembly by the combination of apickup roller3b, and apressing member3ckept pressed against thepickup roller3b, and are conveyed further inward by a conveyingmeans3f.

The toner image formed on thephotoconductive drum7 in the process cartridge B is transferred onto therecording medium2 by applying voltage to atransfer roller4 as a transferring means. Then, therecording medium2 is conveyed to a fixing means5 by the conveyingmeans3f.

The fixing means5 comprises: a drivingroller5a, aheater5b, a supportingmember5c, and arotational fixing member5d. Therotational fixing member5dis a cylinder formed of a sheet of a certain substance, and is supported by the supportingmember5c. Theheater5bis in the hollow of therotational fixing member5d. The fixing means5 fixes the unfixed toner image on therecording medium2 to therecording medium2, by the application of heat and pressure to therecording medium2 while therecording medium2 is passed through the fixing means5. After the fixation, therecording medium2 is further conveyed and discharged into thedelivery area6, by a pair ofdischarge rollers3d.

(Process Cartridge)

On the other hand, the process cartridge B comprises an electrophotographicphotoconductive member7, and a minimum of one processing means. As for the processing means, there are, for example, a charging means8 for charging the electrophotographicphotoconductive member7, and a developing means10 for developing a latent image formed on the electrophotographic member.

Referring toFIGS. 1 and 2, the process cartridge B in this embodiment comprises thephotoconductive drum7, as an electrophotographic photoconductive drum, having a photoconductive layer, acharge roller8 as a charging means, a developingmeans10, and anexposure opening9. In operation, while thephotoconductive drum7 is rotated, the peripheral surface of thephotoconductive drum7 is uniformly charged by the application of voltage to thecharge roller8, and the uniformly charged portion of the peripheral surface of thephotoconductive drum7 is exposed to an optical image projected from theoptical system1, forming a latent image. Then, the latent image is developed by the developingmeans10.

The developing means10 in this embodiment comprises a toner-storage developing means frame10f1, a frame lid10f2, a rotational toner-conveyance roller10bas a toner-conveying means, adevelopment roller10d(in which amagnet10cis stationarily disposed) as a rotational developing member, and adevelopment blade10e. The toner-storage developing-means frame10f1 and the frame lid10f2 are joined, creating a toner chamber (toner storage)10ain which toner (magnetic single-component developer) is stored, and adevelopment chamber10i. In operation, the toner in thetoner chamber10ais sent out into thedevelopment chamber10ithrough the opening (toner passage)10kof the toner-storage developing-means frame10f1, by the toner-conveyance roller10b. In thedevelopment chamber10i, thedevelopment roller10dis rotated, and a layer of triboelectrically charged toner is formed on the peripheral surface of therotating development roller10d. Then, the toner is transferred onto the peripheral surface of thephotoconductive drum7 from the toner layer on thedevelopment roller10d, in the pattern of the latent image on thephotoconductive drum7, developing the latent image into a visual image, that is, a toner image.

Next, the toner image is transferred onto therecording medium2 by the application of a voltage, opposite in polarity to the toner image, to atransfer roller4. The transfer residual toner, that is, the toner remaining on thephotoconductive drum7 after the toner-image transfer, is recovered during the following rotational cycle of thephotoconductive drum7. More specifically, during the following rotational cycle of thephotoconductive drum7, the peripheral surface of thephotoconductive drum7 is charged by thecharge roller8 with the presence of the transfer residual toner on the peripheral surface of thephotoconductive drum7, and another latent image is formed on the peripheral surface of thephotoconductive drum7 by exposure, and then, the residual toner from the preceding rotational cycle of thephotoconductive drum7 is recovered by the fog-prevention bias (difference Vback between the potential level of the DC voltage applied to the developing apparatus and the surface-potential level of the photoconductive member) during the development of the latent image. In this embodiment, a cleaning means, such as a cleaning blade, for removing the transfer residual toner on thephotoconductive drum7, is not provided.

The process cartridge B, which will be described in more detail later, is removably mounted into the cartridge-mounting portion of the main portion, that is, the main assembly A0, of the image forming apparatus A, while being guided by the pair of guiding portions of the process cartridge B, which are located at the lengthwise ends of the process cartridge B, one for one.

The process cartridge B comprises a drum-holdingframe102, which is one of the main sections of the cartridge frame, and the toner-storage developing-means frame10f1, which constitutes another of the main sections of the cartridge frame. The drum-holdingframe102 and the toner-storage developing-means frame10f1 are joined to form a drum frame unit C and a development unit D.

(Drum Frame Unit C)

Referring toFIGS. 3-7, the drum frame unit C, and the various members, for example, thephotoconductive drum7, thecharge roller8, etc., making up the drum frame unit C, will be described.

Photoconductive Drum7

Referring toFIGS. 5 and 6, thephotoconductive drum7 is provided with adrum gear7a, which is solidly attached to one of the lengthwise ends of thephotoconductive drum7. Thedrum gear7acomprises atriangular coupling portion7a1, a firsthelical gear portion7a2, and a secondhelical gear portion7a3. Thetriangular coupling portion7a1 is a driving-force receiving portion by which the driving force from the image-forming-apparatus main assembly A0 is received, and is in the form of a twisted triangular pillar. The firsthelical gear portion7a2 is a driving-force transmitting portion by which the driving force is transmitted to thecharge roller8. The secondhelical gear portion7a3 is a driving-force transmitting portion by which the driving force is transmitted to the development unit D. Although not shown, to the other lengthwise end of thephotoconductive drum7, a flange is fixed, and to the flange, an electrode for grounding thephotoconductive drum7 is integrally attached.

Thephotoconductive drum7, thecharge roller8, etc., are internally held by the drum-supportingframe102. More specifically, one end of thephotoconductive drum7, from which the driving force is transmitted to thephotoconductive drum7, is rotatably supported by the drum-holdingframe102, with the interposition of aside holder107 integrally comprising a drum bearing107b, and the other end of thephotoconductive drum7 is rotatably supported by the drum-holdingframe102, with the interposition of the drum-supportingshaft100. The diameter of thephotoconductive drum7 is in a range from 20 mm to 40 mm.

The secondhelical gear portion7a3 of thedrum gear7ais located close to one of a pair of spacer rings10m1 and10m2 which determine the distance between the axes of thedevelopment roller10dand thephotoconductive drum7. Therefore, the positional relationship, in terms of a pitch circle, between the secondhelical gear portion7a3 and the development-roller gear10nis precisely maintained.

Charge Roller8

Thecharge roller8 comprises ashaft8b, and acontact portion8a. Thecontact portion8ais placed in contact with thephotoconductive drum7, and is an elastic member formed on the peripheral surface of theshaft8bin a manner to wrap theshaft8b. The measurement of theshaft8bin its axial direction is greater than the measurement of thecontact portion8ain its axial direction, extending beyond both ends of thecontact member8a. The two portions extending from two ends of thecontact portion8a, one for one, will be referred to asshaft portions8b1 and8b2. Theshaft8band thecontact portion8aconstitute integral parts of thecharge roller8. The diameter of thecharge roller8 is in a range of 8-20 mm.

Between the peripheral surface of thephotoconductive drum7 and the peripheral surface of thecontact portion8aof thecharge roller8, a layer of electrically conductive microscopic particles is present. The electrically conductive microscopic particles used in this embodiment are microscopic zinc oxide particles (having a resistance of 1,500Ω·cm, and a permeability of 35%). They are formed by air-classifying the particles (secondary particles) created by applying pressure to particles (primary particles) of zinc oxide, the diameters of which are in a range of 0.1-0.3 μm. They are 1.5 μm in volume-average particle diameter. In terms of particle-size distribution, the particles no more than 0.5 μm in size constitute 35% of the volume, and particles no less than 5 μm in size constitute zero to several percentages of the volume.

Charge Roller Bearings103aand103b

Theshaft portions8b1 and8b2 of thecharge roller8 are fitted with charge-roller bearings103band103a, respectively, which are roughly C-shaped in cross section, and which are in contact with theshaft portions8b1 and8b2, respectively, by their internal surface, with respect to their C-shaped cross sections.

Further, thecharge roller bearings103aand103beach have a locking portion (unshown) which engages with a part of the drum-supportingframe102 in such a manner that enables the assembly comprising thecharge roller8 and charge-roller bearings103aand103bto move relative to thephotoconductive drum7.

Compression Coil Spring104

Between the drum-supportingframe102 and the pair of charge-roller bearings103aand103b, a pair of compression coil springs104, as elastic members, are disposed, one for one. One end of the lengthwise ends of eachcompression coil spring104 is fitted around the spring holder portion of the correspondingcharge roller bearing103a(103b), and the other end is fitted around the corresponding spring holder portion of thedrum supporting frame102. Thecharge roller8 is kept pressed on the peripheral surface of thephotoconductive drum7 by these compression coil springs104.

More specifically, in order to keep the theoretical amount of the penetration of thecharge roller8 into thephotoconductive drum7 at 0.2 mm, a pair of compression springs, each of which exerts an operational load of 340 gf, are disposed on the left and right sides, one for one. The spring constant of eachcompression coil spring104 is equivalent to a compression amount of approximately 3 mm.

In this embodiment, the theoretical amount of the penetration of thecharge roller8 into thephotoconductive drum7 is controlled only by controlling the amount of the pressure applied by the pair of compression coil springs104.

(Structure of Charge Roller Driving Mechanism)

Referring toFIGS. 5-12, the structure of the mechanism for driving thecharge roller8 will be described.FIGS. 7-12 describe the gear train of the process cartridge.

Drum Gear7a

Referring toFIG. 11, thephotoconductive drum7 in this embodiment comprises thedrum cylinder7A and the photoconductive layer coated on the entirety of the peripheral surface of thedrum cylinder7A. To one end of thedrum cylinder7A, adrum gear7ais solidly attached. Thedrum gear7atransmits the rotational driving force to thecharge roller8, and also to thetransfer roller4 and thedevelopment roller10d.

Thedrum gear7ais solidly attached to one end of thedrum cylinder7A, as described above, and its axial line coincides with that of thedrum cylinder7A. Thedrum gear7acomprises thehelical gear portions7a2 and7a3, and ashaft portion7a4. Thehelical gear portions7a2 and7a3 are the gear-proper portions of thedrum gear7a, and are on the outward side of thedrum cylinder7A in terms of the axial direction of thedrum cylinder7A. Theshaft portion7a4 constitutes the center portion of thedrum gear7a, and overlaps thehelical gear portions7a2 and7a3, in terms of the radial direction of thedrum gear7a. In other words, thehelical gear portions7a2 and7a3 are cylindrical, and theshaft portion7a4 is extended in the holes of the cylindrical,helical gear portions7a2 and7a3, with its axial line coinciding with those of the cylindrical,helical gear portions7a2 and7a3. Thus, there is acylindrical gap7a5 between the peripheral surface of theshaft portion7a4 and the internal surfaces of the cylindrical,helical gear portions7a2 and7a3. Thiscylindrical space7a5 constitutes the space into which thebearing portion107bof theside holder107 fits as thephotoconductive drum7 is attached to the cartridge frame (drum-holding frame102), so that theshaft portion7a4 is rotatably supported by the bearingportion107b.

Thedrum gear7aalso comprises thetriangular coupling portion7a1, that is, a projection constituting the coupling means on the cartridge side, which projects from the outward end of theshaft portion7a4. As the process cartridge B is mounted into the apparatus main assembly A0, thisprojection7a1 engages the coupling means of the apparatus main assembly, that is, a driving-force transmitting member200 (FIG.24). More specifically, the driving-force transmitting member200 has a roughly triangular recess, and theprojection7a1 fits into this recess to receive the rotational driving force from the apparatus main assembly A0. Theprojection7a1 is twisted around its rotational axis, and its cross section, perpendicular to its rotational axis, is polygonal. The recess of the driving-force transmitting member200 is twisted around the rotational axis of the driving-force transmitting member200, and its cross section perpendicular to the rotational axis of the driving-force transmitting member200, is polygonal.

Thedrum gear7ain this embodiment is structured so that the end surface of theshaft portion7a4 is on the inward side by an amount of Δ E relative to the outward end surface of thehelical gear7a, more specifically, the end surface of thehelical gear portion7a2. Thus, theprojection7a1 partially overlaps thehelical gear portion7a2 in terms of the radial direction of thehelical gear7a. With the provision of this structural arrangement, thedrum gear7ain this embodiment is wider in terms of its axial direction, being therefore superior, in terms of physical strength as well as meshing ratio, to a drum gear in accordance with the prior arts. Thus, it is possible to produce an excellent image.

Also with the provision of the above-described structural arrangement, theshaft portion7a4 is rotationally supported by the bearingportion107bof theside holder107, which is in thecylindrical space7a5 between the peripheral surface of theshaft portion7a4 and the inward surface of the cylindrical gear-proper portions of thedrum gear7a. Therefore, the repulsive force resulting from the meshing of the gears is caught directly below the teeth of the gears, assuring that the repulsive force does not work in the direction to bend thephotoconductive drum7. Therefore, it is assured that thephotoconductive drum7 is rotationally driven in the preferable manner.

As described above, thedrum gear7ain this embodiment has the firsthelical gear portion7a2, which is on the outward side in terms of the lengthwise direction of thecylinder7A, and the secondhelical gear portion7a3, which is on the inward side. The first and secondhelical gear portions7a2 and7a3 are disposed next to each other, with their rotational axes coinciding. In terms of the diameter at the tooth tip (that is, diameter at the root of the gorge), the firsthelical gear portion7a2 is smaller than the secondhelical gear portion7a3. With the provision of this structural arrangement, the optimal number of teeth can be selected for thedrum gear7a, in accordance with the optimal numbers of revolution of thedevelopment roller10dandcharge roller8.

In this embodiment, the first and secondhelical gear portions7a2 and7a3 are made different in the direction of their twist. More specifically, as seen from the drum side, the firsthelical gear portion7a2 is twisted rightward, whereas the secondhelical gear portion7a3 is twisted leftward. Thus, as thephotoconductive drum7 in the process cartridge B in the image forming apparatus main assembly A0 is rotated, the firsthelical gear portion7a2 pushes the gear, which is being driven by thehelical gear portion7a2, in the direction so as to be opposite from the location of thedrum cylinder7A, that is, in the inward direction with respect to the process cartridge B, whereas the secondhelical gear portion7a3 pushes the gear, which is being driven by thehelical gear portion7a3, in the direction so as to be opposite from the location of thehelical gear7a, that is, in the outward direction with respect to the process cartridge B.

Also in this embodiment, thegear portion110bof a gearedcoupler110, which transmits the rotational driving force to thecharge roller8, is pushed in the direction to be opposite from the location of thegear portion7a2 in terms of the lengthwise direction of thecharge roller8, that is, in the inward direction with respect to the process cartridge B.

Idler Gear111

Anidler gear111 is a step gear having twogear portions111aand111bdifferent in diameter, and is rotationally supported by theshaft102c(FIG.5), which is a part of thedrum supporting frame102. The end portion of theshaft102cis supported by theside holder107, being prevented from being broken off by the force resulting from the driving of theidler gear111 by the gear meshing with theidler gear111.

The twogear portions111band111aof theidler gear111 mesh with thegear portion110bof the gearedcoupler110, and the firsthelical gear portion7a2 of thedrum gear7a, respectively, and transmit the rotational driving force from thedrum gear7ato thegear portion110bof the gearedcoupler110.

Geared Coupler110

The gearedcoupler110 has theaforementioned gear portion110b, and a couplerproper portion110aintegral with thegear portion110b. As will be evident fromFIG. 9, the couplerproper portion110aof the gearedcoupler110 is shaped like a pair of parallel cylinders connected by a roughly rectangular plate placed between their peripheral surfaces. The pair of the cylindrical portions of the couplerproper portion110aare symmetrical with respect to the rotational axis of the couplerproper portion110a. Thegear portion110bof the gearedcoupler110 meshes with theaforementioned idler gear111 and transmits the rotational driving force.

As the rotational driving force is transmitted to thecharge roller8 through the gearedcoupler110, the gearedcoupler110 is subjected to a force generated in the direction perpendicular to the rotational axis of the gearedcoupler110 by theidler gear111 meshing with thegear portion110bof the gearedcoupler110. Thus, in order to minimize the effect of this force, it is desired that the gearedcoupler110 is supported at both ends in terms of its axial direction. Therefore, the gearedcoupler110 is provided with ashaft portion110chaving a predetermined diameter. Theshaft portion110cis between the couplerproper portion110aandgear portion110b, and its rotational axis coincides with that of the gearedcoupler110. It is rotationally borne by the wall of a through hole108 (FIG. 5) of the drum-supportingframe102. As the process cartridge B is driven, thegear portion110bis pushed in the inward direction with respect to the process cartridge B, as described above. Therefore, while the process cartridge B is driven, the inward lateral surface of thegear portion110bof the gearedcoupler110 remains in contact with the lip portion of the throughhole108, assuring that thecharger roller8 remains stable while it is rotationally driven.

Referring toFIG. 5, the gearedcoupler110 is also provided with ahole110dwith a predetermined diameter, which is located on the side opposite to theshaft portion110cin terms of the axial direction of the gearedcoupler110. The gearedcoupler110 is rotationally supported by theshaft portion106aof a supportingmember106, which is attached to the drum-supportingframe102, along with theside holder107.

The gearedcoupler110 also couples with thefirst coupling portion112aof anintermediary coupler112, and transmits the rotational driving force.

Intermediary Coupler112

FIG. 8 is a sectional view of the coupled combination of the gearedcoupler110, theintermediary coupler112, and acoupler109, illustrating how they arc coupled. The drawing shows only the couplerproper portion110aof the gearedcoupler110, and only the couplerproper portion109cof thecoupler109.

InFIG. 8, the couplerproper portion110ais hatched in order to differentiate the couplerproper portion110afrom the couplerproper portion109c.

Referring toFIG. 9, theintermediary coupler112 is sandwiched between thecoupler109 and gearedcoupler110. Theintermediary coupler112 has asecond coupling portion112b, which is on thecoupler109 side of theintermediary coupler112, and a pair offirst coupling portions112a, which is on the gearedcoupler110 side. Thesecond coupling portion112bis a hole elongated in a direction perpendicular to axial direction of theintermediary coupler112, and into which the couplerproper portion109cfits. Each of the pair offirst coupling portions112ais a hole open at the peripheral surface of thecoupler112, as well as one of the lateral surfaces of thecoupler112. Its bottom wall, in terms of the radial direction of thecoupler112, is rounded, and its bottom wall, in terms of the axial direction of thecoupler112, is flat. The pair offirst coupling portions112aare where the pair of couplerproper portions110a of the gearedcoupler110 fit one for one.

Thefirst coupling portions112b, in the form of an elongated hole, are symmetrical with respect to the rotational axis of theintermediary coupler112, and the pair of thefirst coupling portions112a, in the form of a groove, are symmetrically positioned relative to each other with respect to the axial line of theintermediary coupler112. The first andsecond coupling portions112aand112bare positioned so that the center line of thefirst coupling portions112aparallel to the lengthwise direction of thefirst coupling portion112a, and the center line of each of the pair ofsecond coupling portions112bparallel to the lengthwise direction of thesecond coupling portions112b, do not become parallel to each other, that is, the angle between them does not become zero; preferably, they are positioned so that the two lines become perpendicular to each other, as shown in FIG.8.

Coupler109

In order to receive the force for rotationally driving thecharge roller8, thecharge roller8 is provided with thecoupler109 as a driving-force receiving member, which is attached to one end of theshaft portion8b1 of thecharge roller8. More specifically, one end of theshaft portion8b1 of thecharge roller8 is given a D-shaped cross section, and is put through the D-shaped center hole of thecoupler109.

Thecoupler109 has a pair of the couplerproper portions109cin the form of a cylindrical projection, which are symmetrically positioned relative to each other with respective to the axial line of thecoupler109. These couplerproper portions109cfit into the pair ofsecond coupling portions112bof theintermediary coupler112, one for one, and receive the rotational driving force.

Thefirst coupling portion112aof theintermediary coupler112 is in the form of an elongated hole. Therefore, while theintermediary coupler112 and the gearedcoupler110 are in the properly coupled state, that is, while theprojection110ais properly situated in thehole112a, there is a certain amount of play between the end surface of thecoupling portion112aand the peripheral surface of thecorresponding projection110a, in terms of the lengthwise direction of thecoupling portion112a, allowing theprojection110ato slide in the lengthwise direction of thecoupling portion112a.

Further, the pair ofsecond coupling portions112bare in the form of a groove with an open end extending in the radial direction of thecoupler112. Therefore, while theintermediary coupler112 and thecoupler109 are in the properly coupled state, in other words, while eachprojection109cis properly situated in thecorresponding hole112b, there is a certain amount of play between the internal surface of thehole112band the peripheral surface of thecorresponding projection109c, allowing theprojection109cto slide in the lengthwise direction of thehole112b.

As described above, thecharge roller8 is rotated in such a direction that in the contact area between thecharge roller8 andphotoconductive drum7, the peripheral surface of thecharge roller8 moves in the direction opposite to the direction in which the peripheral surface of thephotoconductive drum7 moves. Therefore they rub against each other, increasing the frequency at which a given point of the peripheral surface of the charge roller8 (photoconductive drum7) comes into contact with the peripheral surface of the photoconductive drum7 (charge roller8).

(Structure of Mechanism forDriving Development Roller10d,Transfer Roller4, and Toner-Conveyance Roller10b)

As described above, thedrum gear7adrives thecharge roller8 with the interposition of theidler gear111 and the gearedcoupler110. It also drives thedevelopment roller10, thetransfer roller4, and the toner-conveying member (conveyance roller)10b, as shown in FIG.10.

As described above, the firsthelical gear portion7a2 indirectly meshes, with the interposition of theidler gear111, with thegear portion110bof the gearedcoupler110 attached to one end of the shaft of thecharge roller8, and transmits the rotational driving force to thecharge roller8. Further, the firsthelical gear portion7a2 meshes with agear4aattached to one end of the shaft of thetransfer roller4, and transmits the rotational driving force to thetransfer roller4 at the same time as it transmits the rotational driving force to thecharge roller8.

The secondhelical gear portion7a3 of thedrum gear7ameshes with thegear10nattached to one end of the shaft of thedevelopment roller10d, and rotationally drives thedevelopment roller10d. Further, thegear10nof thedevelopment roller10dindirectly meshes, with the interposition of anidler gear10t, that is, a step gear, and anidler gear10u, that is, a step gear, with agear10vattached to one end of theconveyance roller10b, and transmits the rotational driving force to theconveyance roller10b.

In this embodiment, thedrum gear7ahas the first and secondhelical gear portions7a2 and7a3, which are different in the direction in which their teeth are twisted, as described above. Thedevelopment roller10dhas the development-roller gear10nattached to one end of thedevelopment roller10d. This development-roller gear10nmeshes with the secondhelical gear portion7a3 of thedrum gear7a, and is rotationally driven by thedrum gear7a, as described above.

Thetransfer roller4 has thetransfer roller gear4aattached to one end of thetransfer roller4. Thistransfer roller gear7ameshes with the firsthelical gear portion7a2 of thedrum gear7a, and is rotationally driven by thedrum gear7a.

For an improvement in positional accuracy, the firsthelical gear portion7a2 of thedrum gear7ain this embodiment is twisted in a direction to push thedevelopment roller10din the outward direction, whereas the secondhelical gear portion7a3 of thedrum gear7ais twisted in a direction to push thecharge roller8 and transferroller4 in the inward direction as described above.

Further, due to the structural constraint of the gear-driving apparatus, the secondhelical gear portion7a3 of thedrum gear7ais smaller in width in terms of its axial direction than the firsthelical gear portion7a2 of thedrum gear7a.

Also in this embodiment, the secondhelical gear portion7a3 of thedrum gear7ais made larger in pitch-circle diameter than thefirst drum gear7a2 of thedrum gear7a.

In this embodiment, the diameter of thephotoconductive drum7 is 24 mm, and the diameter of thecharge roller8 is 18 mm. Further, the diameter of thedevelopment roller10dis 12 mm.

Also in this embodiment, the peripheral velocity of thedevelopment roller10dis roughly 118% of that of thephotoconductive drum7, and the peripheral velocity of thecharge roller8 is roughly 80% of that of thephotoconductive drum7.

Also in this embodiment, thecharge roller8 is rotated in such a direction that in the contact area between thephotoconductive drum7 andcharge roller8, the peripheral surface of thecharge roller8 moves in a direction opposite to the direction in which the peripheral surface of thephotoconductive drum7 moves, and thedevelopment roller10dis rotated in such a direction that in the area in which the peripheral surfaces of thephotoconductive drum7 anddevelopment roller10dare closest to each other, the peripheral surfaces of thephotoconductive drum7 anddevelopment roller10dmove in the same direction. In other words, thephotoconductive drum7 andcharge roller8 rotate in the clockwise direction, and thedevelopment roller10drotates in the counterclockwise direction, as shown in FIG.1. Further, theconveyance roller10bis rotated in the clockwise direction.

Next, referring toFIGS. 13-15, another example of a gear train in accordance with the present invention will be described.

Thehelical drum gear7aof the gear train shown inFIGS. 10-12 has the firsthelical gear portion7a2, which is on the outward side in terms of the lengthwise direction of thecylinder7A, and the secondhelical gear portion7a3, which is on the inward side. In comparison, thehelical gear7aof the gear train shown inFIGS. 13-15 has only one gear portion (similar tohelical gear portion7a2), which plays both the role played by the firsthelical gear portion7a2 of thedrum gear7aof the gear train shown inFIGS. 10-12, and the role played by the secondhelical gear portion7a3 of thedrum gear7ashown inFIGS. 10-12.

Also in the case of the example of a gear train in accordance with the present invention, shown inFIGS. 13-15, thedrum gear7ameshes with theidler gear111, thegear4a, and thegear10n; the outward side of thedrum gear7a, in terms of its axial direction, meshes with theidler gear111 and thegear4a, and the inward side of thedrum gear7ameshes with thegear10n.

The gear train in shown inFIGS. 10-12, and the gear train shown inFIGS. 13-15 are virtually the same in structure, except for the structure of thedrum gear7a. Therefore, the components, members, portions, etc., of the former, which are the same as the counterparts in the latter, are given the identical reference numerals, and they will not be described here.

Next, the structure of the gear train, shown inFIGS. 13-15, for driving thecharge roller8, thetransfer roller4, thedevelopment roller10d, etc., will be described in comparison to the gear train shown inFIGS. 10-12.

(Structure of Side Holder)

Referring toFIGS. 5-7, the structure of theside holder107 will be described.

As described before, theside holder107 has: ahole107afor the reinforcement of theshaft102 for supporting theidler gear111; a bearingportion107bfor rotationally bearing thephotoconductive drum7; and a couple ofjoggles107hand107ifor precisely positioning theside holder107 relative to thedrum holding frame102.

Further, theside holder107 has a throughhole107c(FIG.5), through which an assembly tool for aligning the teeth of thedrum gear7aand the teeth of theidler gear111 is inserted into the internal space of theside holder107, in order to mesh thedrum gear7aandidler gear111 during process-cartridge assembly.

(Assembly of Process Cartridge)

Method for Assembling Drum-Supporting-Frame Unit C

Referring again toFIG. 5, the assembling of the drum-supporting-frame unit C will be described.

First, anelectrical contact member113 for supplying thecharge roller8 with a bias, and a couple of drum-end cleaning members114 (114aand114b), are attached to the drum-supportingframe102. The cleaningmembers114 will be described later in detail.

As described before, theshaft portions8b1 and8b2 of thecharge roller8 are rotationally borne by thebearings103aand103bengaged with the lengthwise end portions of the drum-supportingframe102. More specifically, theshaft portion8b2, that is, the shaft portion on the electrical-contact-member side, is fitted with the bearing103aformed of electrically conductive plastic, and the bearing103ais attached to a predetermined portion of the drum-supportingframe102, with the interposition of aspring104 for keeping thecharge roller8 pressed upon thephotoconductive drum7. Theshaft portion8b1, that is, the shaft portion on the side with no electrical contact member, is fitted with the bearing103bformed of plastic, and thebearing103bis attached to another predetermined portion of the drum-supportingframe102, with the interposition of thespring104 for keeping thecharge roller8 pressed upon thephotoconductive drum7.

Next, one end of theshaft8b1 of thecharge roller8 is fitted with theaforementioned coupler109 and theintermediary coupler112 in this order. Then, the end of thecharge roller8 with theelectrical contact member113 is fitted with the bearing103a, and the end of thecharge roller8 with no electrical contact member is fitted with the bearing103b. Thecharge roller8 is coated in advance with the aforementioned electrically conductive microscopic particles.

The gearedcoupler110 is fitted into thehole108 of thedrum supporting frame102, with the coupling portion of the gearedcoupler110 aligned with the elongated hole of theintermediary coupler112.

Theidler gear111 is fitted around the supportingshaft102cof the drum-supportingframe102, while being meshed with thegear portion110bof the gearedcoupler110.

The supportingmember106 is attached to thedrum supporting frame102, while inserting theshaft portion106aof the supportingmember106 into thehole110dof the gearedcoupler110, being therefore precisely positioned relative to the drum-supportingframe102.

Thephotoconductive drum7 is precisely positioned relative to the drum-supportingframe102 with the use of a tool. Then, from the side opposite to the side with the drum gear, the drum-supportingshaft100 is put through thehole102aof the drum-supportingframe102, and the flange of thephotoconductive drum7, solidly fixing the drum-supportingshaft100 to the drum-supportingframe102, and rotationally supporting thephotoconductive drum7. On the drum-gear side, theside holder107 is attached to the drum-supportingframe102, precisely positioning theside holder107 relative to the drum-supportingframe102, while fitting theprojection7a1 of thedrum gear7ainto thehole107bof the side holder, and the bearingportion107binto thecylindrical space7a5 of thedrum gear7a. During this process, a tool for rotating theidler gear111 is inserted through the throughhole107cof theside holder107, and theside holder107 is solidly fixed to the drum-supportingframe102 with the use of small screws, while rotating theidler gear111 by the inserted tool so that the firsthelical gear portion7a2 smoothly meshes with theidler gear111.

The above-described processes completes the assembly of the drum-frame unit C.

(Method forAssembling Developing Means10 and Development Unit D)

Next, referring toFIG. 2, andFIGS. 16-20, the development unit D and developingmeans10 of the process cartridge B will be described in detail.

Referring toFIGS. 2 and 17, the developingmeans10 comprises the toner-storage development-means frame10f1 and the frame lid10f2, which are joined to create the toner chamber (toner-storage portion)10aand thedevelopment chamber10i.

The toner-storage developing-means frame10f1 is provided with theopening10kthrough which the toner in thetoner chamber10apasses when it is supplied to thedevelopment roller10d.

Referring toFIG. 16, when the process cartridge B is brand-new, the toner-passage opening10kof toner-storage developing-means frame10f1 of the process cartridge B is blocked with a multilayer toner-sealingmember27 having a cover-film portion27bthermally welded to the seal-attachment portion of the toner-storage developing-means frame10f1, with the use of laser light. The cover-film portion27bis provided with a thermallyweldable layer31 for fixing the toner-scalingmember27. The details of the structure of the toner-sealingmember27 are well known to the people in this business, and are disclosed in, for example, Japanese Laid-open Patent Application 11-102105, etc. Thus, for the details, this patent application or the like should be referred to.

Referring toFIG. 18, the toner-sealingmember27 is pasted to the seal-attachment portion10h, which extends along the four edges of the aforementioned toner-passage opening10k. In order to unseal the toner-passage opening10k, the toner-sealingmember27 is precut by a laser to a depth of half its thickness, as described above (Japanese Laid-open Patent Application 11-102105).

One lengthwise end of the toner-storage developing-means frame10f1 is provided with a toner inlet (unshown), that is, an opening, through which thetoner chamber10ais filled with toner, and which is sealed with acap10j(FIG. 19) after the filling of thetoner chamber10awith toner.

Next, referring toFIGS. 18 and 19, the process for assembling the development unit D will be described.

In order to assemble the developing means10, first, anend seal10rfor preventing the toner from leaking from the lengthwise ends of thedevelopment roller10d, a sealingmember10sfor preventing toner from leaking from the lengthwise ends of thedevelopment blade10e, and a sheet-like member10zfor preventing toner from scattering from the gap under thedevelopment roller10d, are pasted to the toner-storage developing-means frame10f1 and frame lid10f2, with the use of double-sided adhesive tape, or the like.

Thedevelopment blade10eis solidly fixed to the toner-storage developing-means frame10f1, by the lengthwise ends of themetallic plate portion10e1 of thedevelopment blade10e, with the use of small screws.

One (on the left side inFIG. 19) of the two end members (holding members)10gcovers the gear train comprising: the development-roller gear10n(FIGS. 10 and 11) solidly fixed to one end of thedevelopment roller10dand meshing with the fisthelical gear portion7a2 of thedrum gear7a(FIG. 5) solidly fixed to one end of thephotoconductive drum7; and the twoidler gears10uand10tfor transmitting the driving force from the development-roller gear10nto the conveyance gear (unshown) of the toner-conveyance member10b. Theother end member10g(on the right side inFIG. 19) is provided with a hard tab110g, which will be described later.

Theextended tab portion27a(FIG. 16) of thetoner sealing member27 is folded back at oneend10p(FIG. 18) of the toner-passage opening10k, all the way to the other end of the toner-passage opening10k, and is extended outward through the hole10f11 (FIG. 19) of the toner-storage developing-means frame10f1.

The tabproper portion27a1 of theextended tab portion27aof the toner-sealingmember27 is further extended outward through thehole10g6 of theend member10g, and the throughhole10g4 of thehard tab10g1, so that the surface R (surface coated with sealant layer31) of theextended tab portion27a, shown inFIG. 16, thermally fixable to thehard tab10g1, faces thehandle10g1. The end of the tabproper portion27a1 is thermally fixed to a predetermined area of thehard tab10g1 (FIG.19).

Thehard tab10g1 is an integral part of theend member10g, and is formed so that it can be easily torn off from theend member10g. More specifically, the portion by which thehard tab10g1 is connected to the main structure of theend member10gis made very thin so that thehard tab10g1 can be easily separated from the main structure by bending.

Thehard tab10g1 is integrally formed with theend member10g. Preferably, it is formed of high impact polystyrene (HIPS), acrylonitrile-butadiene polymer (ABS), etc., that is, copolymers containing styrene. Theend portion27a1, or tab proper, of theextended tab portion27ais thermally welded to thehard tab10g1.

The above-described processes complete the description of the development unit D shown in FIG.20.

Referring toFIG. 19, theend member10gis provided with an arm-like portion10g7, which protrudes toward the drum-supportingframe102. The arm-like portion10g7 has ahole10g8, which is in the end portion of the arm-like portion10g7, extending in the lengthwise direction of the process cartridge B. The drum-supportingframe102 and theend member10gcan be joined by putting a pin (unshown) through thehole10g8 of the arm-like portion10g7 of theend member10g, and the unshown hole of the drum-supportingframe102, so that they can be rotated about the pin. The arm-like portion10g7 is also provided with a spring-holdingportion10g9, which protrudes from the top surface of the arm-like portion10g7, and a compression coil spring is placed in the compressed state between the arm-like portion10g7 and drum-supportingframe102, with one end of the compression coil spring fitted around the spring-holdingportion10g9. The end portions of thedevelopment roller10dare fitted with gap maintaining members (spacers) (10m1 and10m2), one for one, and the spacers are pressed on the peripheral surface of thephotoconductive drum7. Therefore, a predetermined distance is kept between the peripheral surfaces of thedevelopment roller10dandphotoconductive drum7.

Referring toFIGS. 19 and 21, in this embodiment, the spacers10m1 and10m2 are in the form of a cap, and each end of thedevelopment roller10dis fitted with the cap-like spacer10m1 or10m2. The center portion of the peripheral surface of the cap-like spacer, in terms of its axial direction, having a predetermined width, is raised in relation to adjacent portions of the peripheral surfaces, and, this portion is pressed on the peripheral surface of thephotoconductive drum7.

The development unit D and the drum frame unit C are joined, as described above, to complete the process cartridge B.

(Structure of Cleaning Member114)

While a toner image is transferred from thephotoconductive drum7 onto therecording medium2, and/or while therecording medium2 bearing the unfixed transferred image is conveyed to the fixing means5 and enters the fixing means5, toner particles sometimes float in the image-forming-apparatus main assembly, although by only a very small amount.

Some of the floating toner particles adhere to thephotoconductive drum7, even across the portion corresponding in position to the cap-like spacers10m1 and10m2. As the toner particles adhere to the portion of thephotoconductive drum7 corresponding to the cap-like spacers10m1 and10m2, they are compressed onto the peripheral surface of thephotoconductive drum7 by the cap-like spacers10m1 and10m2, being sometimes semi-permanently adhered in the agglomerated form to the peripheral surface of thephotoconductive drum7, because the cap-like spacers10m1 and10m2 are kept pressed upon the peripheral surface of thephotoconductive drum7 by the force from the aforementioned springs. Some of the agglomerations of toner particles remain on the portion of thephotoconductive drum7 corresponding to the cap-like spacers10m1 and10m2, and gradually grow, until the service life of the process cartridge expires.

The presence of the above-described agglomerations of toner particles on the portion of the peripheral surface of thephotoconductive drum7 corresponding to the cap-like spacers10m1 and10m2 change the distance between thephotoconductive drum7 and thedevelopment roller10d, negatively affecting the development of the latent image on thephotoconductive drum7. Further, as thedevelopment roller10drides over the agglomerations of toner particles, vibrations occur, presenting a possibility that an image defect will occur due to the pitch, in terms of the direction perpendicular to the direction in which therecording medium2 is conveyed, being randomly disturbed.

In this embodiment, therefore, in order to remove the toner particles adhering to the end portions of thephotoconductive drum7 which the corresponding cap-like spacers10m1 and10m2 contact, one-piece cleaning members114 (114aand114b) are attached to the end portions of the drum-supportingframe102, one for one, with the use of double-sided adhesive tape, in such a manner that the cleaningmembers114 contact the peripheral surfaces of the right and left lengthwise ends of thephotoconductive drum7, one for one.

As for the preferable materials for the cleaningmember114, there are:

• (1) a laminar combination of an elastic layer, for example, a layer of foamed polyurethane or felt, and a layer of nonwoven fabric fixed to thereto;
• (2) a laminar combination of an elastic layer, for example, a layer of foamed polyurethane or felt, and a layer of felt, as toner removing layer, fixed thereto;
• (3) a laminar combination of an elastic layer, for example, a layer of foamed polyurethane or felt, and a layer of pile fixed thereto;
• (4) a combination of foamed urethane, and high density polyurethane fixed thereto;
• (5) felt;
• (6) foamed polyurethane; or
• (7) nonwoven fabric. When the laminar materials such as the above (1), (2), or (3), are used as the material for the cleaningmember114, the cleaningmember114 is disposed so that the nonwoven fabric, felt layer as the toner-removing layer, or pile, is placed in contact with thephotoconductive drum7.

These cleaningmembers114 are capable of reliably taking into the nonwoven-fabric portion or the like, the stray toner particles having adhered to the peripheral surface of thephotoconductive drum7, without causing the stray toner particles to fall within the apparatus main assembly; in other words, they can remove the stray toner particles on thephotoconductive drum7 in a preferable manner, reducing frictional resistance as much as possible, preventing, thereby, the increase in the driving force (rotational driving force) necessary to rotate thephotoconductive drum7.

Next, referring toFIG. 21, the positional relationships between the above-describedcleaning member114 attached to thedrum supporting frame102, and thephotoconductive drum7, and between the cleaningmember114 andcharge roller8, will be described.

The adhesion of the stray toner particles, such as the above-described floating toner particles, to the portions of thephotoconductive drum7, outside the changing range of thecharge roller8, that is, the portions of thephotoconductive drum7 extending outward beyond the ends of thecharge roller8, may result in the contamination of the image edges and/or recording-medium edges by the stray toner particles.

Referring toFIG. 21, in this embodiment, each end of thedevelopment roller10dis capped with the cap-like spacers10m1 and10m2, the raised center portion10m3 of which is kept pressed on the peripheral surface of thephotoconductive drum7. The cleaning members114 (114aand114b) are disposed in alignment with the cap-like spacers10m1 and10m2), respectively, in terms of the direction perpendicular to the axial direction of the photoconductive drum7 (charge roller8,development roller10d), with the presence of a gap between the cleaningmember114 and corresponding cap-like spacers10m1 and10m2.

In other words, referring toFIGS. 5 and 21, in terms of the lengthwise direction of thephotoconductive drum7, the range Ca, across which the raised center portion of the cap-like spacer10m1, of thedevelopment roller10d, is in contact with the left end portion of the peripheral surface of thephotoconductive drum7, falls within the range of thefirst cleaning member114adisposed in contact with the left end portion of the peripheral surface of thephotoconductive drum7. Further, theinward edge114a1 of thefirst cleaning member114ais outside the range Ld, in terms of the lengthwise direction of thephotoconductive drum7, across which the development process is carried out by thedevelopment roller10d, and inside the range Lc, across which thecharge roller8 is in contact with thephotoconductive drum7.

Also referring toFIGS. 5 and 21, similarly, in terms of the lengthwise direction of thephotoconductive drum7, the range Cb, across which the raised center portion of the cap-like spacer10m2, of thedevelopment roller10d, is in contact with the right end portion of the peripheral surface of thephotoconductive drum7, falls within the range of thesecond cleaning member114bdisposed in contact with the right end portion of the peripheral surface of thephotoconductive drum7. Further, theinward edge114b1 of thesecond cleaning member114bis outside the range Ld, in terms of the lengthwise direction of thephotoconductive drum7, across which the development process is carried out by thedevelopment roller10d, and inside the range Lc, across which thecharge roller8 is in contact with thephotoconductive drum7.

With the provision of the above-described structural arrangement, the toner particles adhering to thephotoconductive drum7 can be removed by taking them into the first andsecond cleaning members114aand114b.

Therefore, the stray toner particles do not agglomerate on the peripheral surface of thephotoconductive drum7, across the areas corresponding to the ranges across which the cap-like spacers10m1 and10m2 remain in contact with thephotoconductive drum7. Therefore, the distance between thephotoconductive drum7 and thedevelopment roller10dis kept constant, making it possible to form an excellent image.

In particular, not only does the usage of a laminar material, for example, a laminar combination of a layer of elastic substance and a layer of nonwoven fabric, as the material for thecleaning members114 make it possible to prevent the stray toner particles from adhering to thephotoconductive drum7, across the areas corresponding to the ranges across which the cap-like spacers10m1 and10m2 remain in contact with thephotoconductive drum7, without increasing the component count, but also the usage of a laminar material produces a sturdy and resilient cleaning member, improving assembly quality and efficiency. In other words, not only does it make it possible to form an excellent image, but also it makes it possible to minimize the cost of the process cartridge B.

Further, the above-described structural arrangement makes it possible for the first andsecond cleaning members114aand114bto remove the toner particles adhering the peripheral surface of thephotoconductive drum7, across the range in which thephotoconductive drum7 is not charged, that is, outside the range across which thecharge roller8 is in contact with thephotoconductive drum7. Therefore, toner particles are prevented from adhering to the image edges and/or recording medium edges. Therefore, it is possible to form an excellent image.

In this embodiment, the pair of cleaning members114 (114aand114b) are disposed in contact with the lengthwise ends of thephotoconductive drum7, one for one. However, it may be only one of lengthwise ends of thephotoconductive drum7 that is provided with the cleaningmember114.

(Mounting and Removal of Process Cartridge B, into and from, Image Forming Apparatus Main Assembly)

In order to form an image, the process cartridge B assembled as described above is mounted into the image forming apparatus main assembly A0. Next, referring toFIG. 22-27, it is described how the process cartridge B is mounted.

As described before with reference toFIG. 20, as thehard tab10g2 is separated from the end member of the development unit D of the process cartridge B, and is pulled in the direction indicated by the arrow mark, the toner-sealingmember27 is pulled out of the process cartridge B, allowing the toner to be supplied into thedevelopment chamber10i; the process cartridge is readied.

As will be understood with reference toFIG. 4 in addition toFIG. 26, theside holder107 attached to the cartridge frame (drum-supporting frame102) of the process cartridge B is provided with an arcuate portion (first engagement portion)107d, as a guide, by which the process cartridge B is guided when it is mounted into the image forming apparatus main assembly A0; and an arcuate portion (second engagement portion)107e, as a rotation-control portion, which controls the attitude of the process cartridge B when the process cartridge B is mounted into the image forming apparatus main assembly A0. Thearcuate portion107dis at the bottom of the cartridge frame, and the center of its curvature coincides with the axial line of thephotoconductive drum7, whereas thearcuate portion107eis located at the comer of theside holder107.

In terms of the drum-shaft direction of the development unit D, thearcuate portion107dis on the outward side of the drum unit D, but, as seen from the drum-shaft direction, it partially overlaps with the drum unit D. Also, in terms of the drum-shaft direction, the rotation-control portion107eis on the outward side of the drum unit D, and, as seen from the axial direction of thephotoconductive drum7 of the development unit D, it falls within the projection of the development unit D. Further, in terms of the direction in which the process cartridge B is inserted into the image forming apparatus main assembly A0, the rotation-control portion107eis on the trailing side of thearcuate portion107d.

In this embodiment, thetriangular coupling portion7a1, which receives the driving force from the image forming apparatus main assembly A0, is on the inward side of theside holder107, in terms of the drum-shaft direction. With this positional arrangement, the process cartridge B does not need to be provided with dedicated positioning portions, such as thecover portion50 of thetriangular coupling portion7a1 andprojection51 of the process cartridge in accordance with the prior arts, shown inFIG. 31, which function as a positioning portion (positioning boss CB) and a guide, respectively. Therefore, it is possible to make the cartridge size smaller compared to a cartridge in accordance with the prior arts.

Referring toFIGS. 22 and 24, the image-forming-apparatus main assembly A0 is provided with a guiding portion Ga as a first guide which guides the process cartridge B into the image-formation position (properly mounted position), by the aforementionedarcuate portion107dand rotation-control portion107eof the process cartridge B; thearcuate portion107dand the rotation-control portion107eare rested on the guiding portion Ga and are allowed to slide thereon.

On the other hand, the process cartridge B is provided with aprojection102afor covering the drum-supportingshaft100, and aprojection102bfor controlling the process-cartridge position during the mounting or removal of the process cartridge B. Theprojections102aand102bprotrude from the end surface of the drum-supportingframe102 on the side opposite to the end surface with theside holder107, in terms of the drum-shaft direction, as will be easily understood with reference toFIG. 3 in addition toFIGS. 22 and 24.

Further, referring toFIGS. 23 and 25, the image-forming-apparatus main assembly A0 is provided with a guiding portion Gb as a second cartridge guide on the main-assembly side, which coordinates with theside holder107 in order to maintain the attitude of the process cartridge B set by theside holder107 so that the process cartridge B does not become tilted relative to the drum-shaft direction.

Next, referring toFIGS. 22-25, the steps to be followed in order to mount the process cartridge B into the image-forming-apparatus main assembly A0 will be described.

First, alid6awhich also serves as adelivery tray6 of the image forming apparatus main assembly A0 is opened to expose the guiding portions Ga and Gb of the apparatus main assembly A0. Then, the process cartridge B is to be held so that itsarcuate portion107dand the rotation-control portion107eare on the front and rear sides, respectively, as indicated by the single-dot line inFIGS. 22 and 23. Then, thearcuate portion107dand the rotation-control portion107eare to be rested on the first guiding surface Ga1, the front portion of which is somewhat undulatory, while holding the process cartridge B in the above-described manner. On the other side, therefore, theprojections102aand102bof the process cartridge B are rested on the first guiding surface Gb1 of the guiding portion Gb.

Then, the process cartridge B set in the above-described manner is to be pushed into the image forming apparatus main assembly A0.

As the process cartridge B is pushed, thearcuate portion107dand the rotation-control portion107eof the process cartridge B are guided to their designated image-formation positions, while sliding on, and being thereby guided by, the second guiding surface Ga2 of the guiding portion Ga, which is roughly perpendicular to the first guiding surface Ga1, the third guiding surface Ga3 of the guiding portion Ga, which roughly horizontally extends from the bottom of the second guiding surface Ga2, and the fourth guiding surface Ga4 of the guiding portion Ga, which extends from the inward end of the third guiding surface Ga3 in an arcuately dipping manner.

As a result, the process cartridge B rests on the third guiding surface Ga3, with itsarcuate portion107dbeing in contact with the fourth guiding surface Ga4, as a first portion of catching and supporting the process cartridge B, and the curved surface of the rear portion of the rotation-control portion107ebeing in contact with the second guiding surface Ga2, as shown in FIG.26. In this state, thetransfer roller4 and thephotoconductive drum7 have come into contact with each other, and therefore, the process cartridge B has come under pressure working in the direction indicated by an arrow mark in FIG.26. As a result, thethird contact portion107gis placed in contact with the second guiding surface Ga2 adjacent to the third guiding surface Ga3, preventing the positional deviation of the process cartridge B. Thethird contact portion107gmay be either integral with the second contact portion (rotation-control portion)107e, or discrete.

On the other hand, theprojections102aand102b, which are on the other side of the process cartridge B, are guided to their designated image-formation positions while sliding on, and being thereby guided by, the second guiding surface Gb2 of the guiding portion Gb, which is roughly perpendicular to the first guiding surface Gb1, the third guiding surface Gb3 of the guiding portion Gb, which roughly horizontally extends from the bottom of the second guiding surface Gb2, and the fourth guiding surface Gb4 of the guiding portion Gb, which extends from the inward end of the third guiding surface Gb3 in an arcuately dipping manner.

As a result, the process cartridge B rests on the third guiding surface Gb3, with itsprojections102aand102bbeing between the fourth guiding surface Gb4, as a second portion for catching and supporting the process cartridge B, and the second guiding surface Gb2, as shown in FIG.28.

As a result, the process cartridge B is mounted into the proper position in the apparatus main assembly. Next, thelid6aof the image-forming-apparatus main assembly A0 is to be closed. As thelid6ais closed, thetriangular coupling portion7a1 of the cartridge B couples with the driving-force transmitting member200, shown inFIG. 24, having the roughly triangular twisted hole, allowing the rotational driving force to be transmitted from the image-forming-apparatus main assembly A0 to the process cartridge B.

As a result, the process cartridge B is rotated about the rotational axis of thetriangular coupling portion7a1 having coupled as shown inFIG. 27, which coincides with the rotational axis of thephotoconductive drum7. Consequently, gaps x and y are created between thearcuate portion107dandcontact portion107gof the process cartridge B, and the fourth guiding surface Ga4 and second guiding surface Ga2 of the guiding portion Ga, respectively, and the rotation-control portion107eof theside holder107 comes into contact with the third guiding surface Ga3, as a regulating surface, of the guiding portion Ga, fixing thereby the attitude of the process cartridge B in terms of the rotation of the process cartridge B about the rotational axis of thephotoconductive drum7.

On the other side of the process cartridge B in terms of the drum-shaft direction, as the process cartridge B is mounted into the image-forming-apparatus main assembly A0, theprojection102aof the drum-supportingframe102, the axial line of which coincides with that of thephotoconductive drum7, settles into the U-shaped groove, as a cartridge-positioning portion, that is, the fourth guiding surface Gb4, and is kept there by the force generated by the resiliency of thetransfer roller4 and the force from a spring (unshown) for preventing the formation of a blurred image traceable to the driving of the process cartridge B. As for the other projection, that is, theprojection102b, of the drum-supportingframe102, it is designed in position and size so that after the proper mounting of the process cartridge B into the image-forming-apparatus main assembly A0, it remains in non-contact with the image-forming-apparatus main assembly A0, as long as the component dimension errors and assembly errors of the image-forming-apparatus main assembly A0 are within the normal tolerance.

The above-described attitude of the process cartridge B is the attitude in which the process cartridge B is kept during an image-forming operation. Thus, an image-forming operation can be started as soon as the process cartridge B assumes this attitude in the image-forming-apparatus main assembly A0.

In order to extract the process cartridge B from the image-forming-apparatus main assembly A0, the above-described cartridge mounting steps are to be carried out in reverse. As the process cartridge B is pulled, the process cartridge B comes out of the apparatus main assembly, with thearcuate portion107dand the rotation-control portion107esliding on the guiding portion Ga, and theprojections102aand102bsliding on the guiding portion Gb. During this process of extracting the process cartridge B from the image-forming-apparatus main assembly A0, thearcuate portion107d, and thetop surface107fopposing the rotation-control portion107eacross the cartridge mounting space, function as the cartridge-position controlling means on theside holder side107 side, and theprojections102aand102bfunction as the cartridge-position controlling means on the side opposite to theside holder107 side.

In particular, when the process cartridge B is removed from the image-formation position, theprojection102bcomes into contact with the fifth guiding surface Gb5, which is the top surface of the guiding portion Gb, preventing thereby the front side of the process cartridge B, in terms of the cartridge-extraction direction, from rotating upward more than a predetermined angle.

It is not mandatory that the contours of the above-described first, second, and third contact portions of the process cartridge B are as described above. For example, the first and second contact portions may be polygonal (202 and201, respectively) as shown in FIG.29. Further, the second contact portion may haveridges203 as shown inFIG. 30, as long as the counters of these contact portions perform the above-described cartridge-positioning functions. It is preferable, however, that the first, second, and third contact portions of the process cartridge B are arcuate, because when they are arcuate, a part of the second contact portion is allowed to come into contact with the fourth guiding surface Ga4, even if the process cartridge B deviates in attitude due to the tolerance in component dimension.

The above-described embodiment of the present invention is compatible with various well-known developing methods, for example, the two-component magnetic-brush developing method, the cascade-developing method, the touch-down developing method, cloud developing, etc.

As for the electrophotographic photoconductive substance compatible with the above described embodiment, such a photoconductive substance as amorphous silicon, amorphous selenium, zinc oxide, titanium oxide, and various organic photoconductors, can be included. Incidentally, the photoconductive drum in this embodiment comprises a cylinder formed of aluminum alloy or the like, and a layer of photoconductive substance is placed on the entirety of the peripheral surface of the cylinder by deposition, painting, or the like.

As for the material for the drum-supporting frame, the toner-storage developing-means frame, frame lid, etc., of a process cartridge in accordance with the present invention, there are such plastics as polystyrene, ABS (acrylonitrile-butadiene-styrene copolymer), denatured PPE resin (polyphenylene-ether), denatured PPO resin (polyphenylene oxide), polycarbonate, polyethylene, polypropylene, etc.

The above-described process cartridge is, for example, a cartridge comprising an electrophotographic photoconductive member, a developing means, and at least one more processing means. In other words, the present invention is compatible with: a cartridge in which an electrophotographic photoconductive member, a developing means, and a charging means are integrally disposed, and which is removably mountable in the main assembly of an image forming apparatus; a cartridge in which an electrophotographic photoconductive member and a developing means are integrally disposed, and which is removably mountable in the main assembly of an image forming apparatus; and the like, in addition to the process cartridge B in the above-described embodiment of the present invention.

In other words, the present invention is also compatible with: a cartridge in which an electrophotographic photoconductive member, and a charging means or a developing means, are integrally disposed, and which is removably mountable in an image forming apparatus; a process cartridge in which a charging means, a developing means, and an electrophotographic photoconductive member are integrally disposed, and which is removably mountable in an image forming apparatus; and a cartridge in which a minimum of a developing means and an electrophotographic photoconductive member are integrally disposed, and which is removably mountable in an image forming apparatus.

The image forming apparatus in the above described embodiment of the present invention is a laser-beam printer. However, the application of the present invention is not limited to a laser-beam printer. In other words, the present invention is also applicable to various image forming apparatuses other than a laser-beam printer, for example, an electrophotographic copying machine, a facsimile apparatus, a wordprocessor, etc., which is obvious.

As described above, the present invention makes it possible to more reliably mount a process cartridge into the main assembly of an image forming apparatus, and remove the process cartridge therefrom, compared to the prior arts. Further, the present invention makes it possible to more accurately position a process cartridge relative to the main assembly of an image forming apparatus, compared to the prior arts. Further, the present invention makes it possible to keep a process cartridge more stable in attitude during an image-forming operation, compared to the prior arts.

While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.

Claims (21)

1. A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, said process cartridge comprising:

an electrophotographic photosensitive drum;

a process device actable on said electrophotographic photosensitive drum;

a first contact portion, provided on a bottom surface of a cartridge frame portion of said process cartridge, the cartridge frame portion being provided at one longitudinal end of said electrophotographic photosensitive drum and configured and positioned to support one longitudinal end portion of said electrophotographic photosensitive drum,

wherein said first contact portion is guided by a first main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to a mounting position in the main assembly of the apparatus,

wherein said first contact portion is disposed at a leading portion of said process cartridge with respect to a mounting direction in which said process cartridge is mounted to the mounting position, and said first contact portion is mounted to contact a first main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position;

a cartridge coupling disposed above said first contact portion when said process cartridge is mounted to the mounting position, said cartridge coupling being engageable with a main assembly coupling provided in the main assembly of the apparatus to receive a rotational driving force from the main assembly of the apparatus;

a second contact portion provided on the bottom surface of the cartridge frame portion of said process cartridge provided at the one longitudinal end of said electrophotographic photosensitive drum,

wherein said second contact portion is disposed upstream of said first contact portion with respect to the mounting direction,

wherein said second contact portion is effective to limit rotation of said process cartridge in a rotational direction of said electrophotographic photosensitive drum when said process cartridge mounted to the mounting position receives the rotational driving force from the main assembly of the apparatus; and

a positioning portion projected outwardly from another cartridge frame portion of said process cartridge, the another cartridge frame portion being provided at the other longitudinal end of said electrophotographic photosensitive drum and being configured and positioned to support the other longitudinal end portion of said electrophotographic photosensitive drum,

wherein said positioning portion is guided by a second main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position of the main assembly of the apparatus, and is positioned to contact a second main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position.

2. A process cartridge according toclaim 1,

wherein said process device further comprises a charging roller configured and positioned to electrically charge said electrophotographic photosensitive drum, and a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum and wherein the main assembly of the apparatus includes a transfer roller configured and positioned to transfer a developed image formed on said electrophotographic photosensitive drum onto a recording material, and

wherein the rotational driving force is effective to rotate said electrophotographic photosensitive drum, said charging roller, said developing roller, and the transfer roller.

3. A process cartridge according toclaim 1 or2, wherein a leading side surface of said cartridge coupling is inward of an outer surface of said cartridge frame portion and is provided at the one longitudinal end of said electrophotographic photosensitive drum.

4. A process cartridge according toclaim 1 or2, wherein said second contact portion is an arcuate portion disposed at a comer portion of said cartridge frame portion which is provided at the one longitudinal end of said electrophotographic photosensitive drum.

5. A process cartridge according toclaim 1 or2,

further comprising a mounting guide provided on the outside of the cartridge frame portion and which is provided at the other longitudinal end of said electrophotographic photosensitive drum,

wherein said mounting guide is disposed upstream of said positioning portion with respect to the mounting direction, and

wherein when said process cartridge is mounted to the mounting position, said mounting guide is guided by the second main assembly guide.

6. A process cartridge according toclaim 1,

wherein said process device further comprises a charging roller configured and positioned to electrically charge said electrophotographic photosensitive drum, and a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum, and wherein the main assembly of the apparatus includes a transfer roller configured and positioned to transfer a developed image formed on said electrophotographic photosensitive drum onto a recording material,

wherein said process cartridge further comprises a first helical gear and a second helical gear juxtaposed in the longitudinal direction of said electrophotographic photosensitive drum in the order named on the leading portion of said process cartridge with respect to the mounting direction and disposed above said first contact portion when said process cartridge is mounted to the mounting position,

wherein said first helical gear is disposed on an outer side of said electrophotographic photosensitive drum,

wherein when said process cartridge is mounted to the mounting position, said first helical gear is effective to transmit, to the transfer roller, a rotational driving force for rotating the transfer roller and to transmit, to said charging roller a rotational driving force for rotating said charging roller, and

wherein said second helical gear is spaced from the outer side of said electrophotographic photosensitive drum, and

wherein when said process cartridge is mounted to the mounting position, said second helical gear is effective to transmit, to said developing roller, a rotational driving force for rotating said developing roller.

7. A process cartridge according toclaim 1,

wherein said process device further comprises a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum.

wherein the cartridge frame portion is a drum supporting frame,

wherein one longitudinal end of said electrophotographic photosensitive drum is supported by the drum supporting frame,

wherein one longitudinal end of said developing roller is supported by a developing device frame of said process cartridge, and

wherein said drum supporting frame is disposed outside said developing device frame with respect to the longitudinal direction of said electrophotographic photosensitive drum.

8. A process cartridge according toclaim 1, wherein said positioning portion, when said process cartridge is removed from the mounting position, contacts an upper surface of the second main assembly guide to prevent upward rotation of a leading side of said process cartridge beyond a predetermined degree with respect to a removing direction in which said process cartridge is removed from the mounting position.

9. An electrophotographic image forming apparatus for forming an image on a recording material, to which a process cartridge is detachably mountable, said apparatus comprising:

(i) a first main assembly guide provided in a main assembly of said electrophotographic image forming apparatus;

(ii) a first main assembly receiving portion provided in the main assembly of said electrophotographic image forming apparatus;

(iii) a second main assembly guide provided in the main assembly of said electrophotographic image forming apparatus;

(iv) a second main assembly receiving portion provided in the main assembly of said electrophotographic image forming apparatus; and

(v) a mounting portion configured and positioned to detachably mount a process cartridge, which includes an electrophotographic photosensitive drum, a process device actable on the photosensitive drum, and a first contact portion provided on a bottom surface of a cartridge frame portion of the process cartridge, the cartridge frame portion being provided at one longitudinal end of the photosensitive drum and configured and positioned to support one longitudinal end portion of the photosensitive drum, the first contact portion being guided by said first main assembly guide when the process cartridge is mounted to a mounting position in the main assembly of said electrophotographic image forming apparatus, wherein the first contact portion is disposed at a leading portion of the process cartridge with respect to a mounting direction in which the process cartridge is mounted to the mounting position, and wherein the first contact portion is mounted to contact said first main assembly receiving portion provided in the main assembly of said electrophotographic image forming apparatus when the process cartridge is mounted to the mounting position, the process cartridge further including a cartridge coupling disposed above the first contact portion when the process cartridge is mounted to the mounting position and engageable with a main assembly coupling provided in the main assembly of said electrophotographic image forming apparatus to receive a rotational driving force from the main assembly of said electrophotographic image forming apparatus, and a second contact portion provided on the bottom surface of the cartridge frame portion of the process cartridge provided at the one longitudinal end of the photosensitive drum, the second contact portion being disposed upstream of the first contact portion with respect to the mounting direction, wherein the second contact portion is effective to limit rotation of the process cartridge in a rotational direction of the photosensitive drum when the process cartridge mounted to the mounting position receives the rotational driving force from the main assembly of said electrophotographic image forming apparatus, wherein the process cartridge further includes a positioning portion projected outwardly from another cartridge frame portion of the process cartridge, the another cartridge frame portion being provided at the other longitudinal end of the photosensitive drum and being configured and positioned to support the other longitudinal end portion of the electrophotographic photosensitive drum, the positioning portion being guided by said second main assembly guide when the process cartridge is mounted to the mounting position of the main assembly of said electrophotographic image forming apparatus, and being positioned to contact said second main assembly receiving portion when the process cartridge is mounted to the mounting position.

10. A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, said process cartridge comprising:

an electrophotographic photosensitive drum;

a process device actable on said electrophotographic photosensitive drum;

a first contact portion provided on a bottom surface of a cartridge frame portion of said process cartridge, the cartridge frame portion being provided at one longitudinal end of said electrophotographic photosensitive drum and being configured and positioned to support one longitudinal end of said electrophotographic photosensitive drum,

wherein said first contact portion is guided by a first main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to a mounting position in the main assembly of the apparatus,

wherein said first contact portion is disposed at a leading portion of said process cartridge with respect to a mounting direction in which said process cartridge is mounted to the mounting position, and

wherein said first contact portion is mounted to contact a first main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position; and

a limiting portion, provided on the cartridge frame portion at a position behind said first contact portion with respect to the mounting direction,

wherein said limiting portion is configured and positioned to limit movement of said process cartridge by an urging force applied to said photosensitive drum from a transferring roller provided in the main assembly of the image forming apparatus when said process cartridge is mounted to the mounting position by contact to a main assembly contact portion provided in the main assembly of the apparatus.

11. A process cartridge according toclaim 10,

wherein said process device further comprises a charging roller configured and positioned to electrically charge said electrophotographic photosensitive drum, and a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum, and wherein the transferring roller is configured and positioned to transfer a developed image formed on said electrophotographic photosensitive drum onto a recording material,

wherein said process cartridge further comprises a cartridge coupling engageable with a main assembly coupling provided in the main assembly of the apparatus to receive a rotational driving force from the main assembly of the apparatus,

wherein said cartridge coupling is disposed at a position which is above said first contact portion when said process cartridge is mounted to the mounting position,

wherein when said process cartridge is mounted to said mounting position, said cartridge coupling is engaged with the main assembly coupling to receive a rotational driving force from the main assembly of the apparatus, and

wherein the rotational driving force is effective to rotate said photosensitive drum, said charging roller, said developing roller, and the transferring roller.

12. A process cartridge according toclaim 11, wherein a leading side surface of said cartridge coupling is positioned inward of an outer surface of said cartridge frame portion provided at the one longitudinal end of said electrophotographic photosensitive drum.

13. A process cartridge according toclaim 10 or11,

further comprising a mounting guide provided on the outside of the cartridge frame portion and which is provided at the other longitudinal end of said electrophotographic photosensitive drum,

wherein said mounting guide is disposed upstream of said positioning portion with respect to the mounting direction, and

wherein when said process cartridge is mounted to the mounting position, said mounting guide is guided by a second main assembly guide.

14. A process cartridge according toclaim 10, wherein said process device further comprises a charging roller configured and positioned to electrically charge said electrophotographic photosensitive drum, and a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum, and wherein the transferring roller is configured and positioned to transfer a developed image formed on said electrophotographic photosensitive drum onto a recording material,

wherein said process cartridge further comprises a first helical gear and a second helical gear juxtaposed in the longitudinal direction of said electrophotographic photosensitive drum in the order named on the leading portion of said process cartridge with respect to the mounting direction and disposed above said first contact portion when said process cartridge is mounted to the mounting position,

wherein said first helical gear is disposed on an outer side of said electrophotographic photosensitive drum,

wherein when said process cartridge is mounted to the mounting position, said first helical gear is effective to transmit, to the transferring roller, a rotational driving force for rotating the transferring roller and to transmit, to said charging roller a rotational driving force for rotating said charging roller, and

wherein said second helical gear is spaced from the outer side of said electrophotographic photosensitive drum, and

wherein when said process cartridge is mounted to the mounting position, said second helical gear is effective to transmit, to said developing roller, a rotational driving force for rotating said developing roller.

15. A process cartridge according toclaim 10,

wherein said process device further comprises a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum,

wherein the cartridge frame portion is a drum supporting frame,

wherein one longitudinal end of said electrophotographic photosensitive drum is supported by the drum supporting frame,

wherein one longitudinal end of said developing roller is supported by a developing device frame of said process cartridge, and

wherein said drum supporting frame is disposed outside said developing device frame with respect to the longitudinal direction of said electrophotographic photosensitive drum.

16. An electrophotographic image forming apparatus for forming an image on a recording material, to which a process cartridge is detachably mountable, said apparatus comprising:

(i) a first main assembly guide provided in a main assembly of said electrophotographic image forming apparatus;

(ii) a first main assembly receiving portion provided in the main assembly of said electrophotographic image forming apparatus;

(iii) a main assembly contact portion provided in the main assembly of said electrophotographic image forming apparatus; and

(iv) a mounting portion configured and positioned to mount a process cartridge, which includes an electrophotographic photosensitive drum, a process device actable on the photosensitive drum, and a first contact portion provided on a bottom surface of a cartridge frame portion of the process cartridge, the cartridge frame portion being provided at one longitudinal end of the photosensitive drum and configured and positioned to support one longitudinal end of the photosensitive drum, the first contact portion being guided by said first main assembly guide when the process cartridge is mounted to a mounting position in the main assembly of said electrophotographic image forming apparatus, wherein the first contact portion is disposed at a leading portion of the process cartridge with respect to a mounting direction in which the process cartridge is mounted to the mounting position, and wherein the first contact portion is mounted to contact said first main assembly receiving portion provided in the main assembly of said electrophotographic image forming apparatus when the process cartridge is mounted to the mounting position, wherein the process cartridge also includes a limiting portion, provided on the cartridge frame portion at a position behind the first contact portion with respect to the mounting direction, wherein the limiting portion is configured and positioned to limit movement of the process cartridge by an urging force applied to the photosensitive drum from a transferring roller provided in the main assembly of said electrophotographic image forming apparatus when the process cartridge is mounted to the mounting position mounting by contact to said main assembly contact portion.

17. A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus including a transfer roller configured and positioned to transfer a developed image formed on an electrophotographic photosensitive drum of said process cartridge onto a recording material, said process cartridge comprising:

an electrophotographic photosensitive drum;

a process device actable on said electrophotographic photosensitive drum, wherein said process device comprises a charging roller configured and positioned to electrically charge said electrophotographic photosensitive drum, and a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum;

a first contact portion, provided on a bottom surface of a cartridge frame portion of said process cartridge, the cartridge frame portion being provided at one longitudinal end of said electrophotographic photosensitive drum and configured and positioned to support one longitudinal end portion of said electrophotographic photosensitive drum,

wherein said first contact portion is guided by a first main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to a mounting position in the main assembly of the apparatus,

wherein said first contact portion is disposed at a leading portion of said process cartridge with respect to a mounting direction in which said process cartridge is mounted to the mounting position, and said first contact portion is mounted to contact a first main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position;

a cartridge coupling disposed above said first contact portion when said process cartridge is mounted to the mounting position, said cartridge coupling being engageable with a main assembly coupling provided in the main assembly of the apparatus to receive a rotational driving force from the main assembly of the apparatus;

a second contact portion provided on the bottom surface of the cartridge frame portion of said process cartridge provided at the one longitudinal end of said electrophotographic photosensitive drum,

wherein said second contact portion is disposed upstream of said first contact portion with respect to the mounting direction,

wherein said second contact portion is effective to limit rotation of said process cartridge in a rotational direction of said electrophotographic photosensitive drum when said process cartridge mounted to the mounting position receives the rotational driving force from the main assembly of the apparatus;

a positioning portion projected outwardly from another cartridge frame portion of said process cartridge, the another cartridge frame portion being provided at the other longitudinal end of said electrophotographic photosensitive drum and being configured and positioned to support the other longitudinal end portion of said electrophotographic photosensitive drum,

wherein said positioning portion is guided by a second main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position of the main assembly of the apparatus, and is positioned to contact a second main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position,

wherein the rotational driving force is effective to rotate said electrophotographic photosensitive drum, said charging roller, said developing roller and the transfer roller,

wherein said second contact portion is an arcuate portion disposed at a corner portion of said cartridge frame portion which is provided at the one longitudinal end of said electrophotographic photosensitive drum; and

a first helical gear and a second helical gear juxtaposed in the longitudinal direction of said electrophotographic photosensitive drum in the order named on the leading portion of said process cartridge with respect to the mounting direction and disposed above said first contact portion when said process cartridge is mounted to the mounting position,

wherein said first helical gear is disposed on an outer side of said electrophotographic photosensitive drum,

wherein when said process cartridge is mounted to the mounting position, said first helical gear is effective to transmit, to the transfer roller, a rotational driving force for rotating the transfer roller and to transmit, to said charging roller a rotational driving force for rotating said charging roller, and

wherein said second helical gear is spaced from the outer side of said electrophotographic photosensitive drum, and

wherein when said process cartridge is mounted to the mounting position, said second helical gear is effective to transmit, to said developing roller, a rotational driving force for rotating said developing roller.

18. A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus including a transfer roller configured and positioned to transfer a developed image formed on an electrophotographic photosensitive drum of said process cartridge onto a recording material, said process cartridge comprising:

an electrophotographic photosensitive drum;

a process device actable on said electrophotographic photosensitive drum, wherein said process device comprises a charging roller configured and positioned to electrically charge said electrophotographic photosensitive drum, and a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum;

a first contact portion, provided on a bottom surface of a cartridge frame portion of said process cartridge, the cartridge frame portion being provided at one longitudinal end of said electrophotographic photosensitive drum and configured and positioned to support one longitudinal end portion of said electrophotographic photosensitive drum,

wherein said first contact portion is guided by a first main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to a mounting position in the main assembly of the apparatus,

wherein said first contact portion is disposed at a leading portion of said process cartridge with respect to a mounting direction in which said process cartridge is mounted to the mounting position, and said first contact portion is mounted to contact a first main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position;

a cartridge coupling disposed above said first contact portion when said process cartridge is mounted to the mounting position, said cartridge coupling being engageable with a main assembly coupling provided in the main assembly of the apparatus to receive a rotational driving force from the main assembly of the apparatus;

a second contact portion provided on the bottom surface of the cartridge frame portion of said process cartridge provided at the one longitudinal end of said electrophotographic photosensitive drum,

wherein said second contact portion is disposed upstream of said first contact portion with respect to the mounting direction,

wherein said second contact portion is effective to limit rotation of said process cartridge in a rotational direction of said electrophotographic photosensitive drum when said process cartridge mounted to the mounting position receives the rotational driving force from the main assembly of the apparatus;

a positioning portion projected outwardly from another cartridge frame portion of said process cartridge, the another cartridge frame portion being provided at the other longitudinal end of said electrophotographic photosensitive drum and being configured and positioned to support the other longitudinal end portion of said electrophotographic photosensitive drum,

wherein said positioning portion is guided by a second main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position of the main assembly of the apparatus, and is positioned to contact a second main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position,

wherein the rotational driving force is effective to rotate said electrophotographic photosensitive drum, said charging roller, said developing roller, and the transfer roller; and

a first helical gear and a second helical gear juxtaposed in the longitudinal direction of said electrophotographic photosensitive drum in the order named on the leading portion of said process cartridge with respect to the mounting direction and disposed above said first contact portion when said process cartridge is mounted to the mounting position,

wherein said first helical gear is disposed on an outer side of said electrophotographic photosensitive drum,

wherein when said process cartridge is mounted to the mounting position, said first helical gear is effective to transmit, to the transfer roller, a rotational driving force for rotating the transfer roller and to transmit, to said charging roller a rotational driving force for rotating said charging roller, and

wherein said second helical gear is spaced from the outer side of said electrophotographic photosensitive drum, and

wherein when said process cartridge is mounted to the mounting position, said second helical gear is effective to transmit, to said developing roller, a rotational driving force for rotating said developing roller, and

wherein said positioning portion, when said process cartridge is removed from the mounting position, contacts an upper surface of the second main assembly guide to prevent upward rotation of a leading side of said process cartridge beyond a predetermined degree with respect to a removing direction in which said process cartridge is removed from the mounting position.

19. A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus including a transfer roller configured and positioned to transfer a developed image formed on an electrophotographic photosensitive drum of said process cartridge onto a recording material, said process cartridge comprising:

an electrophotographic photosensitive drum;

a process device actable on said electrophotographic photosensitive drum, wherein said process device comprises a charging roller configured and positioned to electrically charge said electrophotographic photosensitive drum and a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum;

a first contact portion, provided on a bottom surface of a cartridge frame portion of said process cartridge, the cartridge frame portion being provided at one longitudinal end of said electrophotographic photosensitive drum and configured and positioned to support one longitudinal end portion of said electrophotographic photosensitive drum,

wherein said first contact portion is guided by a first main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to a mounting position in the main assembly of the apparatus,

wherein said first contact portion is disposed at a leading portion of said process cartridge with respect to a mounting direction in which said process cartridge is mounted to the mounting position, and said first contact portion is mounted to contact a first main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position;

a cartridge coupling disposed above said first contact portion when said process cartridge is mounted to the mounting position, said cartridge coupling being engageable with a main assembly coupling provided in the main assembly of the apparatus to receive a rotational driving force from the main assembly of the apparatus;

a second contact portion provided on the bottom surface of the cartridge frame portion of said process cartridge provided at the one longitudinal end of said electrophotographic photosensitive drum,

wherein said second contact portion is disposed upstream of said first contact portion with respect to the mounting direction,

wherein said second contact portion is effective to limit rotation of said process cartridge in a rotational direction of said electrophotographic photosensitive drum when said process cartridge mounted to the mounting position receives the rotational driving force from the main assembly of the apparatus;

a positioning portion projected outwardly from another cartridge frame portion of said process cartridge, the another cartridge frame portion being provided at the other longitudinal end of said electrophotographic photosensitive drum and being configured and positioned to support the other longitudinal end portion of said electrophotographic photosensitive drum,

wherein said positioning portion is guided by a second main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position of the main assembly of the apparatus, and is positioned to contact a second main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position,

wherein the rotational driving force is effective to rotate said electrophotographic photosensitive drum, said charging roller, said developing roller, and the transfer roller; and

a mounting guide provided on the outside of the cartridge frame portion and which is provided at the other longitudinal end of said electrophotographic photosensitive drum,

wherein said mounting guide is disposed upstream of said positioning portion with respect to the mounting direction, and

wherein when said process cartridge is mounted to the mounting position, said mounting guide is guided by the second main assembly guide.

20. A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus including a transfer roller configured and positioned to transfer a developed image formed on an electrophotographic photosensitive drum of said process cartridge onto a recording material, said process cartridge comprising:

an electrophotographic photosensitive drum;

a process device actable on said electrophotographic photosensitive drum, wherein said process device comprises a charging roller configured and positioned to electrically charge said electrophotographic photosensitive drum, and a developing roller configured and positioned to develop an electrostatic latent image formed on said electrophotographic photosensitive drum;

a first contact portion, provided on a bottom surface of a cartridge frame portion of said process cartridge, the cartridge frame portion being provided at one longitudinal end of said electrophotographic photosensitive drum and configured and positioned to support one longitudinal end portion of said electrophotographic photosensitive drum,

wherein said first contact portion is guided by a first main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to a mounting position in the main assembly of the apparatus,

wherein said first contact portion is disposed at a leading portion of said process cartridge with respect to a mounting direction in which said process cartridge is mounted to the mounting position, and said first contact portion is mounted to contact a first main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position;

a cartridge coupling disposed above said first contact portion when said process cartridge is mounted to the mounting position, said cartridge coupling being engageable with a main assembly coupling provided in the main assembly of the apparatus to receive a rotational driving force from the main assembly of the apparatus;

a second contact portion provided on the bottom surface of the cartridge frame portion of said process cartridge provided at the one longitudinal end of said electrophotographic photosensitive drum,

wherein said second contact portion is disposed upstream of said first contact portion with respect to the mounting direction,

wherein said second contact portion is effective to limit rotation of said process cartridge in a rotational direction of said electrophotographic photosensitive drum when said process cartridge mounted to the mounting position receives the rotational driving force from the main assembly of the apparatus;

a positioning portion projected outwardly from another cartridge frame portion of said process cartridge, the another cartridge frame portion being provided at the other longitudinal end of said electrophotographic photosensitive drum and being configured and positioned to support the other longitudinal end portion of said electrophotographic photosensitive drum,

wherein said positioning portion is guided by a second main assembly guide provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position of the main assembly of the apparatus, and is positioned to contact a second main assembly receiving portion provided in the main assembly of the apparatus when said process cartridge is mounted to the mounting position; and

a first helical gear and a second helical gear juxtaposed in the longitudinal direction of said electrophotographic photosensitive drum in the order named on the leading portion of said process cartridge with respect to the mounting direction and disposed above said first contact portion when said process cartridge is mounted to the mounting position,

wherein said first helical gear is disposed on an outer side of said electrophotographic photosensitive drum,

wherein when said process cartridge is mounted to the mounting position, said first helical gear is effective to transmit, to the transfer roller, a rotational driving force for rotating the transfer roller and to transmit, to said charging roller a rotational driving force for rotating said charging roller, and

wherein said second helical gear is spaced from the outer side of said electrophotographic photosensitive drum, and

wherein when said process cartridge is mounted to the mounting position, said second helical gear is effective to transmit, to said developing roller, a rotational driving force for rotating said developing roller, and

wherein said positioning portion, when said process cartridge is removed from the mounting position, contacts an upper surface of the second main assembly guide to prevent upward rotation of a leading side of said process cartridge beyond a predetermined degree with respect to a removing direction in which said process cartridge is removed from the mounting position.

21. A process cartridge according toclaim 1,17,18,19 or20, wherein said cartridge coupling includes a twisted projection having a triangular cross-section.

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